"Time, distance the lack of an adequate warning" were some of the factors that prevented the U.S. military from reaching the U.S. Consulate in Benghazi, Libya, before four Americans, including U.S. Ambassador Christopher Stevens, had been killed in the Sept. 11, 2012, attack, Defense Secretary Leon Panetta told a Senate panel today.

Panetta testified at a Senate Armed Services Committee hearing that was investigating the U.S. military response the night of the attack. Panetta told the committee that "time, distance, the lack of an adequate warning, events that moved very quickly on the ground prevented a more immediate response" from U.S. military forces located in Europe and the United States. He also cited a U.S. intelligence "gap" that did not foresee the threat of an attack in Libya.

"They wouldn't have gotten there in time," Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, told the panel. The Pentagon had previously disclosed that a Marine counterterrorism platoon based in Spain was the closest U.S. military force that was moved to Sicily to respond to the attacks that night, but arrived there long after the attack had concluded. A U.S. Special Operations team in Europe, and another one in the United States, were also moved, but long after the attack had ended.

Panetta warned against using the U.S. military as "a global 911 service capable of arriving on the scene within minutes to every possible contingency around the world," saying the armed forces have "neither the resources nor the responsibility" to do so.

Both Panetta and Dempsey explained to the Senate Armed Services Committee Thursday that there was no particular stream of intelligence that indicated an attack on the U.S. diplomatic compound was imminent. Both said there was greater concern about American diplomatic facilities in Sudan, Yemen and Pakistan that day than there was anywhere in Libya.

"I think with regards to those specific individuals that were involved in this attack there was a gap," said Panetta. "We didn't have the intelligence that would have given us a heads-up that this kind of thing was going to happen. And that is something that we do need to pay attention to."

Panetta said the U.S. military's response was determined by the intelligence flow of what was taking place on the ground in Benghazi in the seven hours between the initial attack on the U. S. consulate and the later attack on a CIA annex located two miles away.

"The problem that happens here - and this is something that does need to change - is whether or not we have the best intelligence assets, the best intelligence resources in the areas where we need good information," Panetta told senators.

"We've got a lot of resources that are there…but if you have an area where you don't have resources there, if you don't have good intelligence, then it's going to create a gap" he said.

Panetta later attributed that gap to a prioritizing of endeavors in other countries - including Pakistan, Afghanistan, Somalia and Yemen - over Libya and to a lack of host country capabilities.

Over the course of the four-hour hearing, Panetta warned the automatic budget cuts prescribed in the sequestration legislation would further undermine the Department of Defense's ability to fulfill its responsibility to protect American citizens.

"This will badly damage our national defense and compromise our ability to respond to crises in a dangerous world," Panetta said.

Panetta talked about the steps the Defense Department had taken to prepare for the sequester -- the automatic federal spending cuts scheduled to take effect March 1 -- saying they could be reversed as long as they never go into effect.

"The responsibility to protect our citizens rests with both the administration and the Congress," Panetta said.

Senators who called the hearing wanted Panetta and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, to explain what measures the Pentagon had taken while the attack in Benghazi was taking place and what role the Defense Department should play in embassy security going forward.

A tense exchange between Sen. Lindsay Graham, R-S.C., and Sec. Panetta pointed to the confusion that still exists regarding what took place on the night of the attack.

Graham asked Panetta who was in charge of efforts to protect embassy staff during the attack.

Stumbling, Panetta's response was that the question was more complicated than that.

Later Gen. Dempsey jumped in, explaining that Gen. Carter Ham, the commander of U.S. Africa Command would have been in charge of the operation on the ground once Department of Defense troops were in Libya.

The offical report by the Accountability Review Board examining the U.S. response to the attack found embassy security relied heavily on a local militia that proved inadequate and ineffective.

Sen. Kay Hagan, D-N.C., asked if Panetta was comfortable with how well-trained those forces were. The short answer? No.

"These countries that are going through the transitions that have taken place since their various revolutions, one of the areas that's hurting is the quality of their ability to provide security for the embassies that are located in their countries," Panetta said. "That's a problem that we're having to confront more and more in that area of the world."

Former Secretary of State Hillary Clinton testified before the Senate Foreign Relations Committee two weeks ago about the State Department's role in the security failures that allowed for the attack in Benghazi.

Clinton endured brusque questioning and became emotional herself at times. She once again took responsibility for the State Department's security failures that led to the attack, but she defended the administration's actions that day and in the weeks following the tragedy.

"It's also important to recall that in that same period we were seeing violent attacks on our embassies in Cairo, Sana'a, Tunis, Khartoum, as well as large protests outside many other posts where thousands of our diplomats serve," Clinton told the Senate Foreign Relations Committee.

Panetta made the same point today, saying, "We were also concerned about potential threats to U.S. personnel in Tunis, Tripoli, Cairo, Sana'a and elsewhere that could potentially require a military response."

In his opening remarks Levin asked the outgoing Secretary of Defense to address the threat posed by groups behind the conflict in Algeria.

The hearing is expected to be Panetta's last before he steps down pending the confirmation of his successor, former Sen. Chuck Hagel. On Wednesday Levin announced there would be a delay in the committee's vote on Hagel's nomination, pending the receipt of additional documents requested by some senators.